Members of parliament joined the battle to save Bradford Bulls on Thursday as their former chairman Chris Caisley offered to lead a rescue act.

The crisis-torn Super League club must raise £1million – at least half by 5pm on Friday – or face going into administration with a big tax bill looming.

The Bulls, who have so far received more than £300,000 in pledges, say they were forced to issue a desperate plea for help following pressure from their bank.

On Thursday the parliamentary rugby league group revealed they had written to the chairman of the Royal Bank of Scotland, Sir Philip Hampton, urging him to extend the club's overdraft.

The group's chairman, Greg Mulholland, MP for Leeds north west, said his members reacted with "great dismay" to the RBS actions, which he says "places the club in a dire position" and could "have huge ramifications for the city of Bradford and rugby league generally".

Mulholland said: "We represent all parties and a wide range of constituencies. We are fans of the sport like anyone else.

"The letter to Sir Philip today makes clear that the decision by RBS impacts more than just a commercial body, it has huge consequences.

"The club is doing all it can to respond and I am sure will achieve what it needs to. We have simply asked RBS to extend the overdraft until the club is back on its feet."

Bradford hope to reach their initial target with the aid of a bumper auction at Odsal and a 20,000-plus crowd for the visit of Leeds on Friday, in addition to further pledges from the public.

Mulholland added: "The response from Bulls fans and fans from around the country has been amazing and the whole rugby league family is doing what it can to save the club.

"The response so far shows that the money can be raised so RBS should allow more time so this can happen to allow Bradford Bulls to carry on in Super League, which is in everyone's interests."

The Bradford MP and former sports minister Gerry Sutcliffe added: "The loss of Bradford Bulls would not only have huge impact on rugby league in this country and beyond, it will have a devastating effect on the people of Bradford.

"Bradford has had a rugby league club in various guises since the formation of the Northern Union was formed. We cannot let it die with the stroke of a pen."

Meanwhile, Caisley has offered to orchestrate a rescue plan but insists his successor, Peter Hood, must first step down.

Caisley was at the helm throughout the club's glory years at Odsal in the early days of Super League before leaving in 2006 but he remains the largest single stakeholder with 25% of the shares.